The present invention relates to a curable composition, and more particularly to a curable composition suitable for use of various top coatings for outer walls of buildings, automobiles, household electric appliances, plastics and the like, especially, top coatings for products required to have weatherability, elasticity, flexibility and the like.
Hereinafter, a group containing silicon atom bonded to a hydrolyzable group is referred to as "hydrolyzable silyl group", and a vinyl polymer (monomer) having the hydrolyzable silyl group is referred to as "hydrolyzable silyl group-containing vinyl polymer (monomer)".
It is known that a hydrolyzable silyl group-containing vinyl polymer cures at ordinary temperature, and the cured product is a resin having good adhesion to inorganic substances such as concrete, glass, steel and aluminium and further having excellent weatherability (refer to Japanese Unexamined Patent Publication No. 36395/1979 and the like).
However, the cured film of the hydrolyzable silyl group-containing vinyl polymer generally has a defect of brittle. Therefore, it has been tried to blend the polymer with a soft component (soft resin) so as to abate the brittle by providing elasticity or flexibility to the film. However, as things are, such trial has not been practical yet by reason that the compatibility of a hydrolyzable silyl group-containing vinyl polymer with a soft component is extremely poor.
An object of the present invention is to provide a curable composition suitable for use of top coating and the like which maintains excellent weatherability and good adhesion inorganic to substances being originally possessed by the hydrolyzable silyl group-containing vinyl polymer, and further has an excellent physical property balance between stain resistance and elongation or that between impact resistance and hardness.
This and other objects of the present invention will become apparent from the description hereinafter.